Primitive humans destroy animal life. An interesting pattern is that they selectively render extinct larger animals, while smaller species survive. This pattern has been seen all around the world.

Waves of extinctions are shown by those who study animal bones, with large animals dying off much more than smaller ones. This has been shown for Australia, NZ, both North and South America, Madagascar, and numerous islands. These extinctions happen after humans arrive, and selectively remove larger species.

The reference above points out a further point. Humans evolved in Africa, and Africa has smaller animals than existed in both North and South America before the extinctions. It appears that any larger species are gone by 125,000 years ago. The simplest explanation is that early humans (or even genus Homo before sapiens ) wiped out the larger ones in Africa.

Humans probably hunted all the species, large and small. It's the slow reproduction rate of the larger ones that led to their dying off due to the extra predation. Smaller animals can usually reproduce faster and hide better. Well, not the dodo of course, it reproduced slowly and couldn't hide very well, but those features were due to it living on a small island.

Gord wrote:Humans probably hunted all the species, large and small. It's the slow reproduction rate of the larger ones that led to their dying off due to the extra predation. Smaller animals can usually reproduce faster and hide better. Well, not the dodo of course, it reproduced slowly and couldn't hide very well, but those features were due to it living on a small island.

My own hypothesis is that it is lack of fear that leads to large animal extinctions. Bison, elk and deer would be afraid of wolf size predators and would run. Mammoths, giant sloth, saber tooth cats and the like would not be afraid and would not run. Humans with stone tipped spears and powerful spear throwers are far more lethal than wolves. Thus the large and unafraid animals go extinct.

....and they have low reproductive rates. ..... or is an issue of species survival down to only one variable?

Real Name: bobbo the existential pragmatic evangelical anti-theist and Class Warrior.Asking: What is the most good for the most people?Sample Issue: Should the Feds provide all babies with free diapers?

Lance Kennedy wrote:My own hypothesis is that it is lack of fear that leads to large animal extinctions. Bison, elk and deer would be afraid of wolf size predators and would run. Mammoths, giant sloth, saber tooth cats and the like would not be afraid and would not run. Humans with stone tipped spears and powerful spear throwers are far more lethal than wolves. Thus the large and unafraid animals go extinct.

Don't forget, there were large predators before human arrived. Those species also faced bears and large cats. Dire wolves averaged about 150 lbs, and the American lion was about 25% larger than the modern African lion.

But a wolf or dire wolf would be no threat to the larger animals, and not feared. Humans would be in that size range. Not the bear or lion size range.

I have seen directly the result of evolution away from fear. When I was at the Galapagos Islands, which have no mammal predators, I was able to get to within less than a metre of sea lions, pelicans, and other large sea birds (should I mention their names, since it is boobies ?).

Certainly slow reproduction would not help the survival of larger animals. But we have the question of why mammoths and their ilk died out while bison thrived. The bigger difference, in my view, is fear.

Real Name: bobbo the existential pragmatic evangelical anti-theist and Class Warrior.Asking: What is the most good for the most people?Sample Issue: Should the Feds provide all babies with free diapers?

For obvious reasons, the animals at the top of the food chain are susceptible to all perturbations that occur on lower levels.And the more an animal needs to eat, the more space it needs and the less time it has for anything else.While it is true that hunting big game is just convenient for humans, large animals are also more a risk to start with.

I've come up with a set of rules that describe our reactions to technologies:

Spoiler:

1. Anything that is in the world when you’re born is normal and ordinary and is just a natural part of the way the world works.2. Anything that's invented between when you’re fifteen and thirty-five is new and exciting and revolutionary and you can probably get a career in it.3. Anything invented after you're thirty-five is against the natural order of things.- Douglas Adams

Hunting large animals, EM, is both easier and safer if they show no fear of humans. You can walk up to such an animal without alarming it. While I would be reluctant to do that with a saber tooth cat, a fearless mammoth, mastodon, rhino, or giant sloth would be unlikely to attack, and would be easy to drive a spear into.

humans are omnivores, so they don't fit into a classical food pyramid. And classical hunting methods make use of the fact that animals are scared of humans, allowing a group of noise-makers to drive the prey into a trap- which is better than having a docile creature suddenly becoming enraged.

I've come up with a set of rules that describe our reactions to technologies:

Spoiler:

1. Anything that is in the world when you’re born is normal and ordinary and is just a natural part of the way the world works.2. Anything that's invented between when you’re fifteen and thirty-five is new and exciting and revolutionary and you can probably get a career in it.3. Anything invented after you're thirty-five is against the natural order of things.- Douglas Adams

Try to be a little less snarky. When a person gets snide and is shown to be wrong, it makes them look bad.

African and Indian elephants are small compared to mammoths.

If you compare modern African wild life to that which existed in the Americas before man, it is smaller. The comparison is between equivalents. So compare elephant to elephant. Tiger to tiger. Sloth to its equivalent. The same applies to birds. The moa of NZ and the elephant bird of Madagascar both made ostriches look small.

Until human immigrants with stone weapons wiped them out.

The survival of slow breeders like African elephants makes the slow breeding hypothesis less likely. It is noteworthy, though, that African survivors like the elephant are not fearless. If humans approach them, they react. Either with aggression or by running. Of course, if there was a human generated extinction event in Africa 125,000 years ago, the survivors have had time to evolve new behaviour.

If you compare modern African wild life to that which existed in the Americas before man, it is smaller. The comparison is between equivalents. So compare elephant to elephant. Tiger to tiger. Sloth to its equivalent. The same applies to birds. The moa of NZ and the elephant bird of Madagascar both made ostriches look small.

The size difference is minor. Show with evidence that it is significant.

Show with evidence that North American megafauna were not afraid of, or at least wary of humans.

Show that the climate changes which brought the humans did not adversely affect megafauna habitat.

Keep in mind that not all of the extinctions were megafauna. The giant beaver being a case in point.

The biggest problem with the humans-did-it as the sole explanation is that it does not explain why humans-didn't-did-it elsewhere. Most of the humans-did-it (except NZ) is nothing more than post hoc ergo propter hoc reasoning.

. . . with the satisfied air of a man who thinks he has an idea of his own because he has commented on the idea of another . . . - Alexandre Dumas 'The Count of Monte Cristo"

There is no statement so absurd that it has not been uttered by some philosopher. - Cicero

Mass extinctions followed the arrival of humans in the Americas, Australia, NZ, Madagascar, Hawaii, the Caribbean, and many smaller places. Africa is unproven as yet. The reference I posted suggested a mass extinction in Africa 125,000 years ago, but we need more data on that.

Humans appear to have been responsible even for the extinction of our Neanderthal brothers. Maybe others of genus Homo ?

There are people of great naievity who refuse to believe this of indigenous people. I hope you are not that naive.